I want to print the following object, which is a difference between two DateTimes
datetime_diff = datetime2 - datetime1
The type of datetime_diff appears to be Milliseconds. That means it can be printed, but produces the following output which is not human readable
86398979 milliseconds
Sorry for asking such a basic question, but I cannot figure out how to format this in a more readable way.
Something like HH:MM:SS would be ideal.
Managed to figure this out…
datetime1 = DateTime(2024, 10, 24, 9, 0, 0)
datetime2 = DateTime(2024, 10, 24, 9, 30, 0)
datetime_diff = datetime2 - datetime1
ms = Millisecond(datetime_diff) # btw: it is already of type Millisecond
time = Dates.Time(canonicalize(Dates.CompoundPeriod(ms)).periods...)
datetime_diff_str::String = Dates.format(time, "HH:MM:SS")
println("$(datetime_diff_str)")
However, it’s not great and I wish there was a more direct way to do such a thing. I would like to contribute something to the Dates library in Julia. I will put it on my list of things to do, and hopefully I will have some time to get around to it…
I’ve also found some alternative approaches which may be useful to some.
julia> using Dates
julia> ms = Millisecond(12345678)
12345678 milliseconds
julia> Dates.value(ms)
12345678
julia> typeof(Dates.value(ms))
Int64
julia> i = Dates.value(ms)
12345678
# get number of seconds, minutes, hours etc
# by performing truncating division on the integer value
# formed from the number of milliseconds and then
# converting to the correct explicit type
# in other words:
# 1. get Milliseconds object
# 2. convert to integer type
# 3. truncating division
# 4. create Second/Minute/Hour type from integer value
# this is a "unitless" approach
julia> Second(div(i, 1000))
12345 seconds
julia> Minute(div(i, 1000 * 60))
205 minutes
# alternatively you can do it in a way which maintains the units
julia> Millisecond(12000) / Millisecond(1000)
12.0
julia> Millisecond(12000000) / Millisecond(1000 * 60)
200.0
julia> Millisecond(12000000) / Millisecond(1000 * 60 * 60)
3.3333333333333335
julia>
Aha - and you can go further:
julia> Millisecond(12345678) / Second(1)
12345.678
julia> Millisecond(12345678) / Hour(1)
3.429355
All this code can be boiled down to:
t = Dates.Time(canonicalize(datetime_diff))
println("$t")
This was one of my earlier approaches, but I found that it didn’t work.
julia> dt1 = DateTime(2024, 10, 22, 9, 30)
2024-10-22T09:30:00
julia> dt2 = DateTime(2024, 10, 22, 10, 1)
2024-10-22T10:01:00
julia> Dates.Time(canonicalize(dt2 - dt1))
ERROR: MethodError: no method matching Int64(::Dates.CompoundPeriod)
The type `Int64` exists, but no method is defined for this combination of argument types when trying to construct it.
It will work if you load, in addition to Dates.jl, the package CompoundPeriods.jl.
Ok thank you, I will suggest my organization add that.